Re: [PATCH v2 2/6] dt-bindings: dma: dw: Add max burst transaction length property

Serge Semin
2020-05-11T20:05:36Z

On Fri, May 08, 2020 at 02:12:42PM +0300, Andy Shevchenko wrote:
> On Fri, May 08, 2020 at 01:53:00PM +0300, Serge Semin wrote:
> > This array property is used to indicate the maximum burst transaction
> > length supported by each DMA channel.
>
> > + snps,max-burst-len:
> > + $ref: /schemas/types.yaml#/definitions/uint32-array
> > + description: |
> > + Maximum length of burst transactions supported by hardware.
> > + It's an array property with one cell per channel in units of
> > + CTLx register SRC_TR_WIDTH/DST_TR_WIDTH (data-width) field.
> > + items:
> > + maxItems: 8
> > + items:
>
> > + enum: [4, 8, 16, 32, 64, 128, 256]
>
> Isn't 1 allowed?

Burst length of 1 unit is supported, but in accordance with Data Book the MAX
burst length is limited to be equal to a value from the set I submitted. So the
max value can be either 4, or 8, or 16 and so on.

-Sergey

>
> > + default: 256
>
> --
> With Best Regards,
> Andy Shevchenko
>
>